Fix HTTP shutdown cleaning up shell servers with active sessions.

Author: terrorbyte

c2/httpserveshell/httpserveshell.go

@@ -112,9 +112,13 @@ func (serveShell *Server) Shutdown() bool {
 	// Each of the shell sessions and httpservefile sessions should be handled by the channel Shutdown
 	// atomic.
 	if serveShell.SSLShell {
-		sslshell.GetInstance().Channel().Shutdown.Store(true)
+		if !sslshell.GetInstance().Channel().HasSessions() {
+			sslshell.GetInstance().Channel().Shutdown.Store(true)
+		}
 	} else {
-		simpleshell.GetServerInstance().Channel().Shutdown.Store(true)
+		if !simpleshell.GetServerInstance().Channel().HasSessions() {
+			simpleshell.GetServerInstance().Channel().Shutdown.Store(true)
+		}
 	}
 	httpservefile.GetInstance().Channel().Shutdown.Store(true)